AdminLocale.php

<?php namespace App\Http\Middleware;

use Closure;
use Config;
use Illuminate\Http\Request;
use Session;

class AdminLocale
{

	public function handle(Request $request, Closure $next)
	{
		if (($request->getHost() == getenv('APP_DOMAIN')) && preg_match('/\/admin/', $request->url()))
		{
			if ( ! Session::has('admin.locale'))
			{
				$locales = Config::get('translatable.locales');
				Session::put('admin.locale', $request->getPreferredLanguage($locales));
			}

			app()->setLocale(Session::get('admin.locale'));
		}

		return $next($request);
	}

}